Can a blended family's parenting plan specify separate bedrooms or space arrangements for stepsiblings?

A parenting plan generally isn't the right document to specify household living arrangements like bedroom assignments, since that's a practical, day-to-day matter that falls within whichever parent's authority over their own home during their own parenting time, rather than something the other parent or a court typically has a say in. Courts are unlikely to get involved in dictating this level of household detail unless it becomes an actual best-interests concern, such as an arrangement that's genuinely inappropriate or harmful for the children involved given their ages.

That said, if living arrangements involving stepsiblings are a real concern for one parent - for example, wanting assurance that children of different ages or backgrounds have appropriate separate space - that's a conversation worth having directly between the parents, and it can be reflected in a parenting plan as a general expectation if both parents agree it matters, rather than a detailed specification a court will enforce. If this issue is causing real friction or a genuine welfare concern, raise the specifics with a family lawyer, since a serious concern about a child's home environment can be relevant to a broader parenting dispute even if it isn't typically written into a plan as its own clause.